How are texture maps imported into Blender?
Cycles is node based, meaning the material is comprised of nodes. Unlike the blender internal where you go to a different tab and add textures, in cycles everything can be done from with in the node editor.

First make sure you are using cycles. To use Cycles, it must be set as the active render engine in the top header. 
Open the node editor, change the node type to Shader Nodes You should now see something like this.


You can drag your textures from any file browser in to the node editor. That will create a new Image Texture node for each image.
Here is the whole node tree.

The color or diffuse map would go straight in to the Color socket of the Diffuse BSDF node, but because we are adding a AO map, cavity, or any black and white map to effect the color, that gets multiplied with the diffuse map then plugged in to the Diffuse BSDF.
The normal map gets plugged in to a Normal Map node, witch goes it to the Normal socket on the Diffuse BSDF.
The bump map is plugged in to a Bump node, which is connected between the normal map and the Diffuse BSDF.